Resins such as polyamide-6,6 are used in molding compositions due to its many excellent properties, i.e. strength, solvent resistance, etc. In applications which require good electrical properties, molded parts may be exposed to severe conditions, such as exposure to electrical discharge or to excessive current leakage across its surface. These conditions require not only that the molded part have flame resistance, but also that the molded part have a high degree of resistance to carbonization upon exposure to high voltage, i.e. good track resistance and a high degree of resistance to electrical discharge.
However, it has been a problem that flame retarded polyamide resins have poor track resistance compared to the non-flame retarded resin. U.S. Pat. No. 4,559, 372 to Giroud-Abel describes a composition of comprising (i) a polyamide, (ii) a fireproofing amount of red phosphorus, and (iii) an effective amount of at least one lanthanide compound as having improved electrical properties. Other materials mentioned include the incorporation of cupric oxide and cadmium oxide for improved arc resistance. This focus of this patent is on the utilization of red phosphorus.
Hence, it is desirable to provide additional ingredients which can enhance the track resistance of glass fiber polyamide composition, especially flame retardant polyamide compositions.